It is known to test, for example, shock absorbers for life in use by repeatedly moving inner spring-loaded elements relative to outer housings, at predetermined cycling frequency, while imposing a predetermined side force on them.
Two types of prior art device supplied a collar around the shock absorber and applied a side force by a sidewise pulling on the collar through a cable. In one, the cable was put in tension by a weight, to which it ran over a pulley. In the other, the tension was applied hydraulically.